Genetics has provided one of the most discerning and powerful approaches to the dissection of biological function and Drosophila has served as a major model organism for such analyses, many of which have been probed processes relevant to human health. Now gene inactivation by RNAi is revolutionizing genetic approaches. By making possible extremely rapid whole genome screens, a Genome-wide Drosophila RNAi (dmRNAi) resource will tremendously accelerate genetic studies in Drosophila. The RNAi approach will immediately establish a link between function and molecular data. Furthermore, by establishing a reference collection of double stranded RNAs for these analyses, data gathered in numerous laboratories studying diverse problems can be assembled into a common functional data base that will encourage discovery of novel connections. Building on successful construction of an incomplete library of double stranded RNAs representing most conserved genes of Drosophila, we will first establish a complete library. We will then develop approaches to reduce cost, facilitate distribution, encourage use and increase the flexibility of the methods. We will explore methods for the preparation of RNA on a genome-wide scale at an accessible cost structure. Finally, a tagging strategy will be explored as an approach that should allow compression of complex libraries by allowing pooling of DNA templates such that a library of 14,000 constructs can be stored and retrieved from 5 tubes. The library itself and the proposed technical advances will lead the way in making the power of gene inactivation by RNAi available widely by providing a complete collection covering the entire Drosophila genome, facilitating the accrual of data into a common data base, reducing the cost of these studies, and minimizing the technical impediments to initiating genome-wide RNAi screens. Three products will be commercialized under this funding: (1) DNA constructs representing all of the Drosophila genes for use in generating RNA, (2) RNA from the DNA constructs that are RNAi 'ready', and (3) a series of pools available under the genome tagging strategy useful in screening the entire genome. [unreadable] [unreadable]